use mysql SUM() in a WHERE clause

Question

suppose I have this table

id | cash 
1    200
2    301
3    101
4    700

and I want to return the first row in which the sum of all the pre

Answer 1

Not tested, but I think this will be close?

SELECT m1.id
FROM mytable m1
INNER JOIN mytable m2 ON m1.id < m2.id
GROUP BY m1.id
HAVING SUM(m1.cash) > 500
ORDER BY m1.id
LIMIT 1,2

The idea is to SUM up all the previous rows, get only the ones where the sum of the previous rows is > 500, then skip one and return the next one.